AbstractBackground: The importance of maintaining minimal sea lice infestation levels in salmon aquaculture is crucial for fish welfare and the economy in the Faroe Islands. Many methods have been tested, including the use of cleaner fish, such as lumpfish (Cyclopterus lumpus) in salmon cages. However, high mortality rates in lumpfish have led biologists to search for ways to increase cleaner fish welfare.
Objectives: To see what effects shelter color has on lumpfish skin color change over time, as well as shelter color preference and behavior.
Methods: For experiment 1, a sample of 180 lumpfish were split between 18 tanks (10 each tank), which had three shelters of the same color. For experiment 2, a sample of 100 lumpfish were split between 10 tanks (10 each tank), which had three shelters of different colors. The experiments have different methods of collecting data. In experiment 1, images of fishes are examined and data collected with a program called FIJI and analyzed in R. In experiment 2, the placement of the fishes was noted, i.e. which shelter color the fishes were latched on, at the scheduled time of observation.
Results: Experiment 1 (overall data) for hue revealed the biggest change in the tail and black shelters had the influence on color change. For saturation the biggest change was seen in the back and yellow shelters had the greatest influence on color change. For brightness the biggest change was seen in the pectoral fin and white shelters had the greatest influence on color change. Saturation and brightness were not significant until place was added to the model as a three and two way interaction, while hue showed significance in shelter colors over time. Experiment 2 revealed a preference for both red and black shelters.
Conclusion: Lumpfish show a preference for red and black shelters. It is necessary to consider the need of the lumpfish to use color change in salmon farms to best be able to camouflage themselves.
Black and red shelters caused the biggest change in color. In some way, lumpfish choose shelter colors, where they save energy (red) and avoid shelters that are energy costly (white).
|Date of Award
|Eyðfinn Magnussen (Supervisor)